XP on Hit/Kill NPC Not working? No errors?

So I've been trying to get my XP Script to function so if the player's bullet hits the NPC, you gain a certain number of XP, and once you kill that NPC, you gain a certain number as well, yet all my efforts on trying to get this solved haven't worked. Yet, there's no errors in the script, or when ran. So, if anyone knows how to fix this script or what to change, I'd love to the help! Thanks!

function onHealthChanged() 
    local zHuman =  script.Parent:findFirstChild( "Humanoid" )
    if zHuman ~= nil then 
        local tag = zHuman:findFirstChild( "creator" ) 
        if tag ~= nil then 
            if tag.Value ~= nil then 
                local stats = tag.Value:findFirstChild("XP") 
                if stats ~= nil then 
                    if tag.Value.Character ~= nil then 
                        stats.XP.Value = stats.XP.Value + 20 
                    end
                end
            end 
        end 
    end

end 

function onDeath()
    local zHuman =  script.Parent:findFirstChild( "Humanoid" )
    if zHuman ~= nil then 
        local tag = zHuman:findFirstChild( "creator" ) 
        if tag ~= nil then 
            if tag.Value ~= nil then 
                local stats = tag.Value:findFirstChild("XP") 
                if stats ~= nil then 
                    if tag.Value.Character ~= nil then 
                        stats.XP.Value = stats.XP.Value + 200 
                    end
                end
            end 
        end 
    end

end 
script.Parent.Humanoid.Died:connect(onDeath) 
script.Parent.Humanoid.HealthChanged:connect(onHealthChanged)